Dietary fat has been blamed for everything from heart disease to obesity to cancer. For the past 40 years we have been told how bad this macronutrient is for our body. Most diets focus on removing this evil nutrient from our diets. And over the last thirty years Americans have removed fat from their diets. Only problem is we were wrong.
If you don't have a basic understanding of human physiology, biochemistry, or anthropology for that matter (which most Americans don't) and the government and the food industry tells you fat is bad, then you probably will accept that without questioning it. We all did. However, after cutting fat intake, we saw an increase in disease and obesity. Doh! Consider the fact that a recent article in the New England Journal of Medicine found a relationship between the percent of fat in the diet and HDL levels. HDL levels increased as the percent of Calories from fat in the diet increased! There is plenty of support and logic that fat is not bad for you, but is actually very important.
Fatty acids and cholesterol are ubiquitous, essential structural and physiologically active molecules in the body. They make up the cell membranes of every single cell in the body. Fatty acids are important molecules for cell communication (prostaglandins, for example) and make of the myelin (covering) of nerves. Cholesterol, which the body makes upwards of a couple thousand milligrams per day, is the building blocks of important hormones such as testosterone, estrogen, and vitamin D. Additionally, cholesterol is made into bile salts to help emulsify fats (help fat mix with water) in the intestine.
Fat is also a preferred energy source in the body. More than half of our energy comes via oxidized fat while at rest. This percent increases as the time after eating increases. When we exercise vigorously that percent declines simply because we need a faster way of freeing up energy ( therefore greater carbohydrate usage). After we finish exercising vigorously, the percent of energy climbs back up (total energy may be even greater after, for example, after heavy strength training).
Fat's Importance In Energy Balance
Nutrition is a young discipline and is extremely hard to study. Therefore, much we know about fat is very basic. One of the most common arguements against fat is it's higher energy density (than carbohydrates). Fat has more than twice the energy per gram than that from carbohydrates. This measurement can be verified in a physics or chemistry lab.
The issue is, we are not simple furnaces. The body is an extremely sophisticated physiological system. Understanding the complex energy regulation system of the human body has been an elusive task. Simply counting Calories is extremely inaccurate (more on this in the future). For example, the amount and types of gut bacteria can vary actual nutrient availability significantly. Cell metabolism and spontaneous movement both decrease during Calorie restriction.
Viewing the body from a new perspective is warranted. If we now look at the body from an anthropological view, we have a diiferent story. What sort of diet have humans eatened for the majority of their existance? Humans relied heavily on fat. While the total percent varied based on geography and time of year, it comprised the majority of Calories (especially, like large cats, you consider the preferred consumption of brain, organs, and marrow of the kill).
Don't fear the fat. We have been consuming fat for millions of years, yet only in the last fifty years has obesity and chronic disease become an epidemic. Naturally occurring fat (and that includes over 20 different types of fatty acids) are an important part of our nutrition. Unfortunately, they have undeservingly been bashed by 'experts' with perhaps a greater financial interest in you consuming a diet of 50% processed grains.